Measurement and modeling of ablation of the bottom of supraglacial lakes in western Greenland

• Published in: Geophysical research letters Vol. 39; no. 2
• Main Authors: Tedesco, M., Lüthje, M., Steffen, K., Steiner, N., Fettweis, X., Willis, I., Bayou, N., Banwell, A.
• Format: Journal Article Web Resource
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.01.2012; American Geophysical Union; John Wiley & Sons, Inc
• Subjects: Ablation; Cryosphere; Earth sciences; Earth sciences & physical geography; Earth, ocean, space; Exact sciences and technology; Freshwater; Geophysics; Greenland; Ice; Ice cover; Lakes; Melting; Physical, chemical, mathematical & earth Sciences; Physique, chimie, mathématiques & sciences de la terre; Ponds; Sciences de la terre & géographie physique; Summer; supraglacial lakes; Thermodynamic models; Thermodynamics; West Greenland; polar regions; Arctic region; Greenland; ablation; Regional scope; Temperature sensor; Summer; accuracy; melting; ice; Climate models; Ice cover; Modeling; Temperature gradient; Measurement in situ; ice sheets; depth; Thermodynamic model; temperature; data bases
• ISSN: 0094-8276; 1944-8007; 1944-8007
• DOI: 10.1029/2011GL049882

We report measurements of ablation rates of the bottom of two supraglacial lakes and of temperatures at different depths collected during the summers of 2010 and 2011 in west Greenland. To our knowledge, this is the first time that such data sets are reported and discussed in the literature. The measured ablation rates at the bottom of the two lakes are of the order of ∼6 cm/day, versus a rate of ∼2.5–3 cm/day in the case of bare ice of surrounding areas. Though our measurements suggest the presence of a vertical temperature gradient, it is not possible to draw final conclusions as the measured gradient is smaller than the accuracy of our temperature sensors. In‐situ measurements are compared with the results of a thermodynamic model forced with the outputs of a regional climate model. In general, the model is able to satisfactorily reproduce the measured quantities with RMSE of the order of 3–4 cm for the ablation and ∼1.5°C in the case of water temperature. Our results confirm that the ablation at the bottom of supraglacial lakes plays an important role on the overall lake volume with the ablation in the case of ice covered by a lake being 110–135% of that over bare ice at nearby locations. Beside ice sheet hydrological implications, melting at the bottom of a supraglacial lake might affect estimates of lake volume from spaceborne visible and near‐infrared measurements. Key Points Ablation of bottom of supraglacial lake obtained from pressure transducers data Ablation rate at the bottom of a lake is about double that of bare ice The ablation rate and temperature in the lake can be satisfactorily modeled